DESCRIPTION

SCOPE OF THE INVENTION

The present invention relates to a heating group of a fluid, in particular water for domestic use, a heating method and a method for obtaining an improved heating group starting from a traditional heating group.

PRIOR ART

As is known, conventional heating groups, in particular for heating domestic water, comprise: a heat source, a storage tank, configured for containing the domestic water heated by means of the heat source, and a heat exchanger group, comprising a tubular duct in fluid communication with a domestic water supply system, configured for receiving in inlet, from the water network, the domestic water to be heated, and delivering at the outlet towards the storage tank and/or to a usage water system, the sanitary water thus heated. For this purpose, the tubular duct of the heat exchanger is arranged in the vicinity of the heat source.

Typically, a traditional heating group for domestic use comprises a heat pump, which is configured for supplying about 24KW of power in order to heat the domestic water in instantaneous mode, such a domestic water enters the heat exchanger, from the water supply system, at an average temperature of about 12 °C (TIN), and exits from the heat exchanger, to be supplied directly to the utilities of the usage water system at a supply temperature TER or to be stored, in the storage tank, at a storage temperature TAC equal to about 60 °C.

In the storage tank, the temperature TAC of the domestic water is typically maintained around 60 °C also to prevent the proliferation of bacteria inside the tank itself and the heated domestic water, to be supplied to the usage water system, is typically mixed, coming out of the heating group, with cold domestic water, to supply the user with domestic water at a supply temperature TER of about 38 °C or at a lower temperature, depending on the requirements.

These traditional heating groups suffer from some drawbacks. First of all, their consumption is no longer adequate for the current needs, which mainly involve the use of low energy consumption heating groups in the building sector. Currently, for example, the heat pumps used in building construction are configured for supplying at most about 10KW of power and this implies, at the same conditions, the impossibility of reaching such high temperatures in the traditional heating groups for the domestic water leaving the storage tank. This power is in fact not sufficient to guarantee instant hot water which requires about 20 Kw depending on the flow rate, therefore it is necessary to provide a storage tank to meet domestic hot water withdrawals.

Not only that, the energy used to heat the domestic water in the storage tank at 60 °C is not used to the fullest, as there are greater losses due to insulation and the COP of the heat pump at 60° worsens considerably compared to for example to 40 °C.

DESCRIPTION AND ADVANTAGES OF THE INVENTION

The need therefore arises to devise a domestic water heating system, particularly for residential use (for example home, hotel, etc.) to solve or reduce the aforementioned drawbacks and, in particular, the main object of the present invention is that of providing a domestic water heating group, which is an alternative to traditional heating groups.

Another object of the present invention is to provide a domestic water heating group which reduces energy consumption compared to traditional groups.

Yet another object of the present invention is to provide a domestic water heating group that is easy to implement at competitive costs.

A further object of the present invention is to provide a method for heating domestic water which is alternative to traditional methods.

Last but not least, an object of the present invention is to provide a method for obtaining an improved heating group starting from a traditional heating group.

These and further aspects of the present invention are achieved by a heating group of a fluid according to claim 1, by a heating method according to claim 8 and by a method for obtaining an improved heating group according to claim 9.

The dependent claims refer to preferred and advantageous embodiments of the invention.

BRIEF DESCRIPTION OF THE FIGURES

The present invention will now be described, for non limiting illustrative purposes, according to two preferred embodiments thereof, with particular reference to the drawings of the accompanying figures, in which:

Figure 1 shows a first embodiment of a domestic water heating group according to the present invention; and

Figure 2 shows a perspective view of a second embodiment of a domestic water heating group according to the present invention.

In the figures, identical reference numerals will be used for similar elements.

DESCRIPTION OF THE INVENTION

With reference to the accompanying figures, it will be noted that a domestic water heating group according to the present invention is generally indicated with the reference numeral 1 and comprises at least one heat source 2, for example a heat pump or a gas burner in a condensation boiler, and at least one storage tank 3, configured for containing the domestic water heated by the heat source 2.

The storage tank 3 comprises at least one inlet mouth 31 and at least one tubular inlet duct 311 in fluid connection with each other and configured for receiving in inlet heated domestic water. The storage tank 3 further comprises at least one first outlet mouth 32 and at least one tubular outlet duct 321 in fluid connection with each other, configured for supplying the heated domestic water from the storage tank 3.

The heating group 1 according to the present invention further comprises at least one heat exchanger group 4, which in turn comprises at least one tubular duct 41 comprising at least one inlet section 411 and at least one outlet section 412. The inlet duct 41 is in fluid communication with a water supply system 5 of the domestic water, with a usage water system 6 and with the storage tank 3 by means of the tubular duct 311 and the inlet mouth 31, and is configured for receiving in inlet, from the water supply system, at the inlet section 411 thereof, the domestic water to be heated, and for supplying in outlet the domestic water thus heated, at the outlet section 412 thereof, towards the storage tank 3 at a storage temperature TAC and/or towards a usage water supply system 6, at a supply temperature TER.

The tubular duct 41 of the heat exchanger is, for this purpose, thermally coupled to the heat source 2, between the inlet section 411 thereof and the outlet section 412 thereof so that, in use, the heat generated by the heat source 2 can be transferred to the domestic water flowing in the tubular duct 41.

Advantageously, the heating group 1 according to the present invention comprises at least one domestic water mixer group 7, located upstream, with respect to the fluid feeding direction, of the inlet section 411 of the tubular duct 41 of the heat exchanger 4, such a mixer group 7 comprises at least one first inlet port 71, at least one second inlet port 72 and at least one outlet port 73 in fluid connection, respectively, with the water system 5, with the storage tank 3 and with the heat exchanger 4.

More particularly, the mixer group 7 is configured for:

- receiving in inlet the domestic water, at a low temperature TIN (typically 12 °C) coming from the water supply system 5, at the first inlet port 71,

- receiving in inlet the heated domestic water, leaving the first outlet 32 of the storage tank 3, at the second inlet port 72, and

- mixing the domestic water thus received and supplying, at the outlet port 73, in fluid connection with the inlet section 411 of the tubular duct 41 of the heat exchanger 4, the domestic water to be heated thus mixed, having an intermediate temperature TINT, which is between the temperature TIN of the domestic water supplied by the water system 5 and the temperature of the heated domestic water TAC, supplied by the storage tank 3.

A preferred embodiment provides that the storage tank 3 comprises at least one second inlet mouth 37 and at least one tubular duct 371, in fluid connection with each other and configured for drawing by a third outlet mouth 38, the domestic water fed by the water supply system 5, and for restoring the quantity of water drawn from the tank 3 by means of the first outlet mouth 32.

For the management of this power supply there may be a solenoid valve, or the reintegration may be carried out only by exploiting the water inlet pressure which causes the tank 3 to fill with the same amount of hot water taken from the first outlet 32. If one wants to use a particular type of tank referred to as emptying, it will be necessary to manage the reintegration through a solenoid valve.

According to a particularly advantageous aspect of the invention, the mixer group 7 is of the hybrid electronic type and is capable of delivering at the outlet the domestic water to be heated at an intermediate temperature TINT which can be regulated according to the power that can be supplied by the heat source 2, so that, on leaving the heat exchanger, the temperature of the heated domestic water TAC is maintained between 38 °C and 45 °C, preferably between 39 °C and 41 °C, in the storage tank 3 and that the supply temperature TER thereof towards the usage water system 6 is about 38 °C.

In the calculations reported below, reference is made to a heated domestic water temperature TAC equal to 40 °C.

Traditional systems maintain the temperature in the storage tank at 60 °C and therefore make the heat pump work with a high temperature delta which results in a very bad COR On the contrary, by mixing in inlet to the exchanger 4, inlet water and water from the storage tank, as will be better described below, it is possible to use the power of 10 Kw of a heat pump with a more favorable temperature profile and consequently a better COP.

In the heating group 1 according to the present invention, the storage tank 3 comprises at least one second outlet mouth 33, and a tubular duct 331, between the second outlet mouth 33 of the storage tank 3 and the heat exchanger 4, thanks to the which the storage tank 3 is placed in fluid connection with the heat exchanger 4 upstream of the heat source 2 thermally coupled to the heat exchanger.

As will be noted, the inlet mouth 31 and the first outlet mouth 32 of the storage tank are located in the vicinity of the top 34 of the storage tank 3, i.e. distal to the heat exchanger 4, where the temperature of the domestic water is substantially equal to TAC, while the second outlet mouth 33 of the storage tank is closer to the bottom 35 of the storage tank 3, where the temperature of the heated domestic water is typically lower than the temperature of the domestic water in the vicinity of the top of the tank 3.

With such a location of the second outlet mouth 33 and the inlet mouth 31 it is possible to take heated domestic water from the bottom of the tank, heat it in the heat exchanger 4 and feed it back into the storage tank at a temperature of about 40 °C, so to maintain, in use, a substantially constant temperature.

The heat exchanger group 4 clearly comprises at least one flow selector device 42, for example any solenoid valve or any other suitable device, between the tubular duct 331 of the storage tank 3 and the tubular duct 41 of the heat exchanger 4, to allow the introduction into the heat exchanger 4 of the heated domestic water coming from the storage tank 3 or of water at the intermediate temperature TINT coming from the mixer group 7. Correspondingly, the heat exchanger group 4 comprises another flow selector device 43, for example any solenoid valve or any other suitable device, between the tubular duct 311 of the storage tank 3 and the tubular duct 41, for example at the outlet section of the tubular duct 41 of the heat exchanger 4. In this way, it is possible to obtain a water circuit between the storage tank 3 and the heat exchanger 4, to allow the withdrawal of the heated domestic water present on the bottom of the storage tank 3, the heating thereof and the introduction thereof, heated to about 40 °C (TAC), into the storage tank 3.

The heating group 1 according to the present invention, further comprising at least one control unit (not shown in the drawings), operatively connected to the heat source 2, to the storage tank 3, to the heat exchanger 4 and to the mixer group 7, to which it is capable of sending suitable control signals and from which it can receive corresponding response signals.

The control unit is advantageously configured for controlling the mixer unit 7 so that it supplies domestic water at an intermediate temperature TINT, which depends on the power that can be supplied by the heat source and on the supply temperature TER and on the flow rate of the domestic water that one wants to obtain downstream of the heating group, towards the usage water system 6.

Having said that, an object of the present invention is also a method for heating domestic water, which can preferably but not necessarily be implemented with the heating group 1 described above, which comprises the following operating steps:

- mixing domestic water, coming from a feeding water supply system 5, with heated domestic water, coming from a storage tank 3 of a heating group 1, until it is brought to an intermediate temperature TINT between the temperature TIN of the domestic water provided by the water supply system and the temperature of the domestic water provided by the storage tank;

- supplying such a domestic water at said intermediate temperature TINT to a heat exchanger 4 thermally coupled to a heat source 2, thus obtaining domestic water at a supply temperature TER for a usage system 6, in which the intermediate temperature TINT is adjustable depending on the maximum power that can be developed by said heat source 2 and the supply temperature TER and the flow rate (liters/minute) of the domestic water that one wishes to supply to the usage water network 6.

In fact, for example, if the required flow rate is about 7 liters per minute and a power of 10 Kw of the heat source 2 is available, the heating group 1 is capable of raising the water temperature by 21 °C, therefore TINT should be around 19 °C to have as a supply temperature TER equal to about 40 °C; if the required flow rate is about 14 It per minute and a power of 10 Kw of the heat source 2 is available, the heating group 1 is capable of raising the water temperature by 10.5 °C, therefore TINT should be about 29.5 °C to have a supply temperature TER of about 40 °C.

For a better understanding of the invention, a further explanation is now provided by the following formulas:

We indicate with:

E = thermal energy stored in the storage tank 3 (Wh)

Cs = specific water heat (Wh/KgK)

Kg = kilograms of water in the storage tank 3 (Kg)

P = heat source power 2 (W)

Flow rate = quantity of water per hour required by the usage system 6 (Kg/h)

Delta = difference between the domestic water temperature of the storage tank TAC and the intermediate temperature TINT (K)

Delta2 = difference between the intermediate temperature TINT and the supply temperature TER (K) where:

Delta2=P/(Flow rate*Cs) The water at intermediate temperature TINT passing from heat source 2 at power P will increase its Delta2 temperature to reach the required supply temperature TER; the power P of the heat source 2 being fixed and the required flow rate being known, Delta2 is obtained from the second formula which in turn, the supply temperature TER being known, allows obtaining the intermediate temperature TINT following the mixing = TER - Delta2.

The automatic mixer 7 allows the intermediate temperature TINT to be adjusted accordingly.

In addition:

E=Cs*Delta*Kg

Delta = TAC - TINT

TINT= TER - Delta2

E=Cs* TAC - (TER - Delta2) *Kg

Therefore, the energy stored in the tank 3 compared to traditional systems will be lower than Delta2.

Consequently, it is evident from the formulas that it is possible with the same performance to have a tank 3 at a temperature TAC lower than the current ones and precisely of Delta2. Therefore, given the power that can be developed by the heat pump, for example equal to 10KW, it is possible to determine mathematically the intermediate temperature TINT which the domestic water entering the heat exchanger 4 should have, clearly higher than 12 °C supplied by the water supply system 5, to guarantee the required flow rate in liters/min.

Clearly, the raising of the water temperature TIN of the domestic water supplied by the water system 5, up to the value of the intermediate temperature TINT is obtained, according to the present invention, by the mixing group 7, by mixing, in a manner known for the man skilled in the art, domestic water supplied by the water supply system 5 with domestic water coming from the storage tank 3.

Thanks to the introduction of the mixing group 7 upstream of the heat exchanger 4 it is possible to supply domestic water at a supply temperature TER, for example of 40 °C, with a heat source 2 which develops a power much lower than that developed by traditional systems.

Not only that, in the case of a heat pump 2, the coefficient of performance COP increases as the temperature of the domestic water in the storage tank 3 decreases, so that, for a temperature set at 60 °C it is equal to 3.12, while for a temperature set at 40 °C it is equal to 5.26 (at 5 °C room temperature).

The optimal setting of the mixer 7 provides for setting the storage temperature TAC in the tank equal to the supply temperature TER of the hot water so as to always make the heat pump work at the minimum temperature and thus have the highest COP.

Experimental calculations allowed verifying that all this translates into a saving in energy consumption and therefore also costs, in the case of a heat pump, equal to about 68%, and about 10% in the case of a gas burner a condensation boiler.

Finally, as will be noted, the heating group 1 according to the present invention may be advantageously obtained starting from a traditional heating group comprising : at least one storage tank 3, configured for containing the domestic water heated by the heat source 2, wherein the storage tank 3 comprises at least one inlet mouth 31 and at least one tubular inlet duct 311, in fluid connection with each other and configured for receiving in inlet heated domestic water, and at least one first outlet mouth 32 and at least one tubular duct 321, in fluid connection with each other and configured for supplying the heated domestic water from the storage tank 3; as well as at least one heat exchanger group 4, comprising at least one tubular duct 41 having at least one inlet section 411 and at least one outlet section 412, thermally coupled to the heat source 2 between the inlet section 411 thereof and the outlet section 412 thereof, and in fluid communication with a water supply system 5 of domestic water to be heated and a usage water supply system 6 of heated domestic water, wherein the tubular duct 41 is configured for receiving in inlet, from the water supply system 5 , at the inlet section 411 thereof, the domestic water to be heated, and supply in outlet at the outlet section 412 thereof towards the storage tank 3, with which it is in fluid communication by means of the tubular duct 311 and the inlet port 31, and/or towards a usage water system 6 at a supply temperature TER, the domestic water thus heated.

Said method provides for installing at least one mixer group 7 for said domestic water, upstream of the inlet section 411 of the tubular duct 41 of the exchanger group 4, the mixer group 7 having at least one first inlet port 71, at least one second inlet port 72 and at least one outlet port 73 respectively in fluid connection with the water supply system 5, with the storage tank 3 and with the exchanger group 4, in a manner such the mixer group 7, during use:

- receives said domestic water in inlet at low temperature (TIN) at the first inlet port 71 from said water supply system 5,

- receives in inlet the heated domestic water, leaving the first outlet 32 of the storage tank 3, at the second inlet port 72, and

- mixes the domestic water thus received and supplies, at said outlet port 73, in fluid connection with the inlet section 411 of the heat exchanger 4, the domestic water thus mixed, having an intermediate temperature TINT, between the temperature TIN of said domestic water supplied by the water supply system 5 and the temperature of the heated domestic water TAC, supplied by the storage tank (3), and wherein the intermediate temperature TINT is adjustable as a function of the power suppliable by the heat source 2, and of the supply temperature TER and of the flow rate that one wishes to provide for the usage water supply system 6.

In the foregoing, the preferred embodiments have been described and variants of the present invention have been suggested, but it is to be understood that those skilled in the art will be able to make modifications and changes without thereby departing from the relevant scope of protection, as defined by the appended claims.